Pump seals and in particular pump seals for coolant pumps as used in internal combustion engines are used to seal gaps between a rotating shaft and a stationary housing. Such seals are often exposed to large numbers of cycles, heat, vibration, aggressive coolant constituents and debris.
Various designs are known in the art, but currently suffer from being complex to manufacture, expensive or simply not robust enough.
More particularly, mechanical seals have been provided for use with water pumps of heavy duty engines, such as a diesel engine for a truck or other vehicles wherein the mechanical seals for such vehicles preferably are compact and low cost mechanical seals. While mechanical seals of the contacting face type are widely used in many different industries, and are provided in a wide range of sizes, typically mechanical seals used for more complex and large-scale applications, such as industrial pumps, compressors and mixers used in various industrial applications, have a relatively substantial size and a relatively complex construction so as to be capable of use in such industrial applications. These types of mechanical seals used in industrial applications are designed for high-speed revolutions by an equipment shaft such as the shaft of a pump or compressor which is driven by an electrical motor. These types of mechanical seals use relatively rotatable seal rings wherein one comprises a stator typically mounted on an equipment housing, and the second one comprises a rotor which mounts to the shaft, and wherein the contacting, opposed faces of the seal rings define a seal ring region extending radially across the ring faces. However, these mechanical seals as used in industrial applications have relatively large sizes, mounting structure and attendant costs which make such mechanical seals unsuitable for smaller scale applications such as the shaft of a coolant pump/water pump of an internal combustion engine.
It is also known to provide compact and relatively inexpensive mechanical seals that are used for sealing the rotary pump associated with the coolant circulation system of an engine such as a diesel engine and particularly a diesel engine as used on heavy-duty vehicles such as trucks. An example of one such mechanical seal is disclosed in U.S. Pat. No. 5,797,602 (Less).
In a coolant circulation system for a diesel engine, such mechanical seals effect sealing between the pump casing and the rotating drive shaft that is drivingly connected to a pump impeller. In such applications, a coolant circulation system has the pump, which is provided with inlet and outlet passages, respectively, for supplying and discharging liquid coolant to and from the interior of the pump casing. The pump casing has a conventional pumping impeller which is rotatable within the pump casing and drivingly connected to the drive shaft which rotates the impeller about the longitudinal shaft axis. The drive shaft typically is driven from the diesel engine wherein the shaft projects outwardly through a housing section that defines a chamber commonly referred to as a pump bore or stuffing box. It is known to provide a mechanical seal such as the known mechanical seal of the Less '602 patent within the pump bore for preventing leakage of fluid being pumped within the pump casing along the shaft.
In these known mechanical seals, such as that disclosed in the Less '602 patent, the mechanical seal typically includes a pair of annular seal rings which are disposed concentrically in surrounding relationship to the shaft wherein the seal rings have respective annular and generally flat seal faces formed on opposed axial end faces thereof, which seal faces are normally maintained in relatively rotatable sealing contact with one another. One seal ring is typically mounted as the rotating ring or rotor to the shaft by a shaft sleeve and rotates therewith. The other seal ring is non-rotatably supported within an annular shell, which shell is non-rotatably engaged within the pump bore such that the second seal ring serves as a stator that sealingly contacts the rotor or rotating seal ring.
To non-rotatably engage the stationary seal ring to the support shell in the Less '602 patent, an annular sleeve projects forwardly from the pump bore in cantilevered relation therewith and surrounds the seal ring wherein a hexagonal configuration of the sleeve prevents rotation of the stator relative thereto. This design, however, has the sleeve cantilevered forwardly from the shell and has a thin-wall construction so as to still be subject to the substantial torsional vibrations encountered in water pump applications of this type.
A mechanical seal design similar to the '602 patent also has been in use wherein the components are developed from machined metal but are less cost-effective.
It is an object of the invention to provide an improved mechanical seal, which for example, provides an improved drive configuration between a shell and stationary seal ring.